 
 (deftest test-word-count-mem
   (let [outpath (doto (fs/path "tmp/word-count-output") fs/path-delete)
-        dseq (mem/dseq [[nil "apple banana banana"]
-                        [nil "carrot apple"]
-                        [nil "apple"]])
+        dseq (->> [["apple banana banana"]
+                   ["carrot apple"]
+                   ["apple"]]
+                  (mem/dseq :keys))
         dsink (seqf/dsink [Text LongWritable] outpath)
         [result] (word-count (th/config) dseq dsink)]
     (is (= {"apple" 3, "banana" 2, "carrot" 1}

         (r/map #(-> [% 1])))))

(defn word-count-reducer
  [input]
  (->> input mr/keyvalgroups
       (r/map (fn [[word counts]]
                [word (r/reduce + 0 counts)]))))

(defn word-count
  [conf dseq dsink]

(defn word-count-mapper
  [input]
  (let [wc (.getCounter mr/*context* "word-count" "words")]
    (->> input
         (r/mapcat #(str/split % #"\s+"))
         (r/map (fn [word]
                  (returning word
